Method of charging a blast furnace



March 1954 K. c. MCCUTCHEON METHOD OF CHARGING A BLAST FURNACE 4Sheets-Sheet 1 Filed Sept. 24, 1949 INVENTOR.

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BYa v E2 March 1954 K. c. MCCUTCHEON METHOD OF CHARGING A BLAST FURNACE4 Sheets-Sheet 2 Filed Sept. 24, 1949 FIG. 4

. I N VEN TOR. Aewzvsrw C. Me CWEON Anweys BY W, 09M% March 2, 1954 K.c. MCCUTCHEON METHOD OF CHARGING A BLAST FURNACE 4 Sheets-Sheet 3 FiledSept. 24, 1949 u 74 747A 74 Z INVENTOR i6 Aim/57w 6. Me C(IIZ'HEON March2, 1954 c, M CUTCHEON 2,671,017

METHOD OF CHARGING A BLAST FURNACE Filed Sept. 24, 1949 4 Sheets-Sheet 4J 2 M Q I N; W l I g wfi . #1 g a a' E INVENTOR. rfewusru C fikCurcv/smvPatented Mar. 2, 1954 METHOD OF CHARGING A BLAST FURNACE Kenneth C.McCutcheon, Ashland, Ky., assignor to Reserve Mining Company, Babbitt,Minn., a corporation of Minnesota Application September 24, 1949, SerialNo. 117,652

3 Claims.

This invention relates to blast furnaces; more particularly, to a methodfor charging a blast furnace, which, although not limited thereto, isespecially applicable to blast furnaces for reducing iron ores.

In a blast furnace there is counter-current flow of descending materialsand rising gases; that is to say, the solid materials such as ore, flux,and fuel are charged at the top and move downwardly against the flow ofgases which are moving in an upward direction as the result of theintroduction of air and/or other gases under pressure adjacent thebottom. The temperatures of all the solids increase as they descend,reducing gas being formed by the reaction of the oxygen introducedeither in the form of air or as a separate gas with the fuel. Thisreducing gas in its ascension causes reduction of the iron or othermetal and caloination of the limestone or other flux, the reduced metaland resulting gangue being melted adjacent the tuyeres and drawn off,thus making room for the descent of the materials thereabove. The moreintimate the contact of the rising gases with the descending solids ofthe charge, the more rapidly and uniformly are the reactions carried on.Under ideal conditions of operation there would be substantially uniformreaction and downward movement of the charge in all parts of thefurnace, so that no unreduced ore reaches the hearth, the quantity ofcoke or other fuel being only that necessary to maintain the propertemperature and provide a sufficient volume of reducing gas to effectthe reactions. Unfortunately, however, conventional blast furnaces andmethods of charging fall far short of ideal operation, thereby greatlyincreasing the cost of the metal produced as Well as resulting inexcessive wear and tear on the furnace.

Many, if not all, of the difificulties encountered in blast furnaceoperation, for example, slips, hanging, excessive coke consumption andthe like, are directly the result of insufficient or improper contactbetween the ascending gases and the descending solid materials and thisis, in turn, largely the result of improper distribution of the chargewithin the furnace due to undesirable segregations of various componentsof the material. The improper distribution and segregation are, in turn,directly traceable to defects in the method and apparatus conventionallyemployed to introduce or char e the solid materials into the furnace,and/or to the design of the furnace with respect to the area of thestock column adjacent to the point of charging relative to the efiectivearea of the tuyere activity in the smelting zone. Moreover, conventionalcharging methods and apparatus result in excessive flue dust, requiringexpensive equipment for its recovery, which further reduces theefliciency of the operation.

Charging of a conventional blast furnace is eifected by means of adouble bell, each bell forming the bottom of a hopper with the upperbell and hopper generally being smaller than the lower or charging belland hopper into which the upper bell discharges. The upper hoppergenerally has a somewhat larger cubical capacity than the skip or bucketused to hoist the material to the top of the furnace, while the volumeof the charging hopper is usually as large as the conventional round ofmaterials charged, that is, it may hold several skip loads. Inaccordance with theusual procedure, the upper bell is closed when eachskip or bucket load is delivered thereto and is opened to drop this loadinto the charging hopper, with the charging bell closed, when the skipor bucket returns for another load, the charging bell being operatedonly once or twice for each complete charge of materials, commonlyspoken of as a round. The distribution of each skip load of material onthe large or charging bell is dependent upon the slope of the bells, thesize of the charging hopper, sizes of the particles of the materialcharged, and the amount and distribution of the material present in thecharging hopper from previous operations of the smaller bell. Since theskip or bucket does not drop the material uniformly throughout the crosssectional area of the smaller hopper and since different materials havedifferent flow properties and different angles of repose, thedistribution on the small bell is seldom uniform.

The lack of uniform distribution on the small bell results in acorresponding lack of uniformity of distribution of the material on thelarge bell which is further accentuated by the mounds and hollows madeby irregularities of distribution of the material previously depositedupon thelarge bell by operation of the small bell. These irregularitiesin the distribution of the material upon the large bell are notcorrected when the material on the latter is discharged into the furnacesince the particles of the material are not of uniform size. Moreover,the materials charged into the furnace are subjected to rising currentsof gases while dropping from the charging hopper which alter thedistribution of the materials and carry 01f quantities of the fineparticles as dust.

As a. result of the use of a, circular bell, the

ore, being relatively fine and heavy, is concentrated mainly under thelip of the charging bell while the larger particles of coke andlimestone roll against the furnace wall and into the center of the stockcolumn. Broadly speaking, therefore, the stock column has the oredeposited in a somewhat annular layer of generally-doughnut shape,thicker under the lip of the bell with coke above and below, because thecoke occupies about three times the space of the ore in each charge, thecoarse coke and limestone particles being disposed in the center andaround the outer circumference of this doughnut of fine ore. Inaddition, the annulus or doughnut of fine ore. is thicker in somecircumferential locations than in others.

It will be apparent, therefore, that the permeability of the stockcolumn-with respectto the ascending gases is not uniform. The ore, beingmore dense, the layersthereof offer more resistanceto gas flow than acorresponding volume of coke and this resistanceflby the ore layers isincreased when the layers are relatively thick and the ore contains alarge percentage of'fines. Investigations have shown that zones in thestock column offering high resistance to ,gas flow are zones of lowerdegree of reduction than are the more permeable zones and hence, whenore'is charged in the manner just mentioned, apart'of the ore ordinarilymust be reduced by direct contact with incandescent carbon lower down inthe furnace, thus causing excessive coke consumption. Moreover, as thesize of the furnaces has increased, the customary procedure has been toincrease the size of the charging bell and this has increased the volumeof the relatively open center, thus increasing channeling of gasestherethrough with consequent inefificient operation. The usual solutionfor this increased volume of open center has been to increase the sizeof the ore charge and to also charge a part of the ore in the center ofthe furnace to reduce the porosity in'that region. Larger ore charges,however. make the ore layers thicker and hence more impervious, thusfurther contributing to poor gassolid contact and inefiicient operationwhile charging ore to the center ofthe furnace increases the quantity ofore which reaches the smelting zone in an unreduced'state since in the"larger furnaces there is 'an'inactive or dead center centrally of thetuyeres and *extending thereabove.

Investigations have also "shown that'whenthe percent reduction of ironore to metallic iron has reached about 80%, due to the action ofreducing gases,.the iron bearing cempoundsare softand plastic and beginto stick together. Where there is a thick layer of ore, this action iseven-more pronounced and the stock column stops moving loosely andfreely and begins to hang until ;a sufficient cavity is formedtherebelow to set it in motion again. When downward motion does beginagain, the material tends to drop me body and when this action is ofsuiiiicient magnitude, it is called a slip which, as is wellknown,causes excessive dust losses and other difficulties. Prior attempts toovercome .the above mentioned difficulties have been directed primarilytowards changes in the sequence of charges and to the use ofdistributors. These procedures and devices,however, generally produceuniform segregation as contrasted with uniform distribution of thematerials. That is to say, the ore and other materials of the stockcolumn are deposited in the furnace in more or less uniform piles ratherthan as uniform layers and hence, while some improvement is effected inthe operation, optimum conditions cannot be reached or even closelyapproximated. In order to further increase production and effect savingsin coke and flux, it is necessary to improve the gas-solid contact bysecuring more uni-form permeability in the stockcolumnthancanbesecuredby these conventional expedients.

.An object of this invention is to provide an improved method forcharging a blast furnace which=provides=a better distribution of thematerial charged, reduces dusting, and provides better gas-solidcontact, thereby reducing the quantity of fuel consumed per ton of metalproduced andtotherwise increasing the efficiency of operation.

Another object of the invention is to provide an improved method forcharging a blast furnace wherein the ore is charged in relatively thin,substantially uniform layers whichare preferably annular in shape thetransversedimensionsof thelayers being so related to thetransverse..dimensions of the smelting and .tuyerezoneaasto preventhanging and improve the permeability of the stock column.

A further object .of the inventionis-to provide an improvedmethod forcharging .a blast furnace as defined in the preceding .object whereinthe ore is charged in thin layers .betweenlayersof coarser coke, whilethe finer cokeis chargedrinto the center of the furnace.

A still further object of theinvention. is :to provide an improvedmethod forncharginga blastifurnace as defined inthe.twoprecedingparagraphs and wherein the fiux materialismore uniformlydistributed throughout the charge withsubstantially none of thismaterialinthe.centralsection or core of the furnace, thereby promotingmore uniform fiuxing action and preventingthe. center of the charge frombecoming too opener. porous.

An additional object of the invention is .to,pr.o-'- vide an improvedmethod .ior charginglalblast furnacesuch that the ore is depositedwithinthe furnace between two concentric .tubes .withffine coke charged intothe .innertube, whereby .the ore, flux, and coarser cokeare, inrelatively-thin annular layers, of substantially .uniform thickness withfine coke in the center of such amiularlayers.

A still furtherrobject of the inventioniswto provide an improvedmethodfor charging .a blast furnace wherein the materials areperiodically delivered therein without appreciably altering the heightof the stock columnso that. the permeability of the latterremainssubstantially constant.

The invention further. residesin certain novel steps of procedure, andfurtherobjects .andadvantages thereof will be apparent to. thoseskilledin the art to which itpertains fromltheifollowingl description of. an.apparatus bywhich. it may be performed, described with .referenceito theaccompanying drawings .in which. similar reference characters representcorresponding ,parts in the several views .andinwhich:

.Fig. l is a somewhat schematic longitudinal sectional view through theupper portion wot .,a blast surface illustrating an apparatus forperforming the improved ,method of charging;

Fig. 2 is anenlarged view .of .a. .porticnofl-the structure shown inFigL-l illustratingtheadjna table deflector mechanisinpositionedtodeliver material to the central or inner ,tube;

"Figf3 is a transverse sectional viewtakensubstantially on the sectionindicating line 3-.;3 of

Fig. 2 with the charging bell removed and further illustrating theadjustable deflector;

Fig. 4 is a view similar to Fig. 2 but with the deflector mechanismpositioned to deliver material between the inner and outer tubes;

Fig. 5 is an enlarged fragmentary longitudinal sectional view of theupper hopper or supply tube of the furnace illustrating the manner inwhich a fixed deflector may be employed therein;

Fig. 6 is a transverse sectional view takensubstantially on the sectionindicating line 6-6 of Fig. 5;

Fig. 7 is an enlarged fragmentary longitudinal sectional view of theupper hopper or supply tube of the furnace illustrating the manner inwhich a rotatable scraper ormaterial leveling means may be employedtherein;

Fig. 8 is a transverse sectional view taken substantially on the sectionindicating line 88 of Fig. 7;

Fig. 9 is a somewhat schematic longitudinal sectional view through theupper and lower portions of a blast furnace of rectangular cross sectionillustrating a modification of the improved charging method as adaptedto such furnace;

Fig. 10 is a transverse sectional view through the tuyeres of therectangular furnace illustrating the action thereof, the view beingtaken substantially on the line lB-lll of Fig. 9;

Fig. 11 is a fragmentary side elevational view of the upper or supplyhopper, material conveying mechanisms and the material supply bins shownin Fig. 9, the view being taken substantially on the line llll of Fig.9;

Fig. 12 is a top plan view of the upper or supply hopper and bell of thefurnace illustrated in Fig. 9, the view being taken substantially on theline |2-l2 of Fig. 11;

Fig. 13 is a view similar to Fig. 10 but showing a modified arrangementof the tuyres for a rectangular furnace; and

Fig. 14 is a view similar to Figs. 10 and 13 but showing the arrangementof the tuyeres of a furnace having an elliptical cross section.

In accordance with this invention, improved distribution of thematerials charged, and hence improved permeability in the stock columnand better gas-solid contact, is accomplished by cent zone is soarranged as to provide a constant head or height of material within theblast furnace proper, which is unaffected by the sequential operationsof the bells. In addition, the

changes in the top of the furnace and changes in the charging methods.Thus, irregularities in distribution of the material over the smallerIbell, due to the delivery thereto by the skip or bucket, are equalizedby making the cross sectional area of the upper hopper smaller than' inconventional constructions or, alternatively, means are provided in theupper hopper or supply tube to assist the distribution of the materialtherein. Consequently, the material is delivered to the charging bellwith a substantially 1 uniform circumferential distribution. Inaddition, the larger or charging bell is preferably operated separatelyfor each different type of material delivered thereto, i. e., for ore,flux, and coke, so that the different materials are charged sequentiallyin layers into the furnace. Alternatively, the ore, flux, and coarsecoke may be deposited on the large bell and charged together into thefurnace by one drop or operation of the area of the quiescent zone is sorelated to the areas of the smelting and tuyere zones that the flow ofgases is not impeded and the materials moving from the quiescent zonesubstantially maintain their initial distribution within the upperportion of the furnace proper. Also, the materials are delivered in amanner such as to form an annulus of ore with the relatively fine cokepreferably being charged centrally thereof, while the coarse coke andflux materials are intermediate the separate layers of ore. Details ofthe manner in which these operations and results are achieved willbecome apparent from the following description of the present preferredV embodiment of the invention and certain modiflcations thereof.

In Fig. 1 of the drawings the upper portion of a furnace is somewhatschematically illustrated in section. The construction comprises theouter shell 20, lining 2|, and wear plates 22, which are provided over ashoulder of the lining adjacent to the top of the stock line designatedSL. The furnace further comprises a closed top with the usual gasoutlets 23 and 24 intermediate which are provided the hoppers and bellsgenerally designated 25. The charging hopper 25 is formed in aconventional manner, with the lower portion shaped as an invertedfrustum of a cone. The opening at the bottom of this hopper is adaptedto be closed by a conically shaped charging bell 21. Above andconcentric with the charging hopper 25 and charging bell 2! is the feedor supply hopper 28, which is generally of circular cross section buthas an inverted frusto-conical lower portion the opening of which isclosed by the upper or smaller bell 29. Connected with the lower orcharging bell 2? is an actuating rod 30 which extends upwardly throughthe upper bell 29 and through a hollow actuating tube 3| for the latter,the rod 3!! and tube 3! being operated by conventional mechanisms notshown. The furnace and bells just described are of conventionalconstruction with the exception that the feed tube or upper hopper 28 ispreferably of smaller diameter than that normally employed.

In accordance with this invention, the furnace just described isprovided with a downwardly extending impervious partition wall 32 formedof heat-resistant metal and connected with the top of the furnace at itsupper end intermediate the charging hopper 26 and the gas outlets 23,24. Where the furnace is of circular cross section, as shown in Figs.l-3, this partition wall 32 may be in the form of a cylindrical tube,the lower end of which is open and extends downwardly into the furnaceto a point adjacent the wear plates 22. The lower end of the tube orpartition wall 32 may be supported by radially extending bracesIntermediate the charging bell 27 and the upperend of the tube 33, theinterior of the tube 5 This tube 33 is supported from the I 32isprovided with an adjustable deflecting means generally designated 35.As shown in detail in Figs. 2 and 3, this adjustable deflecting meanspreferably comprises a plurality of metal plates or vanes 36, the upperedges of which are hingedly connected, as at 3?, to a portion of thewall or tube 32, the plates extending downwardly from their pivotalconnections in overlapping relationship and being adapted to be inclineddifferent extents, while maintaining their overlapping relationship, todirect material falling from the bell 21 in its descent within the tube32. To effect this adjustment of the deflecting means, a plurality oflinks 38 each has its upper end pivotally connected to the inner wall ofthe tube 32 and its lower end pivotally connected to a shoe member 38.Also pivoted to the shoes 39 are a second set of links 40, the lowerends of which are pivoted to an actuating ring 4|. In the illustratedembodiment, the shoes 39 are shown as separate members for each plate 36with an inclined inner face of each shoe engaging a portion of the rearsurfaces of the corresponding pivoted plate 35. It will be understood,however, that two or more of the separate shoes may be connectedtogether or a ring member formed of a plurality of segments may beemployed in place of separate shoes in which event there need not be aset of links 36 and All for each plate 36. Connected with the actuatingring 4! and extending upwardly therefrom are a plurality of pull rods 42which extend through sealing gaskets such as 43, the upper ends of therods 62 being connected to a ring 54 which is adapted to be movedupwardly and downwardly by mechanism not shown.

In accordance with the preferred procedure of this invention, thematerials such as ore, coke, and flux which are to be charged to thefurnace are delivered to the top thereof in a conventional manner, asfor example, by the use of a skip or bucket, indicated in broken linesat 15 in Fig. 1. Since the feed supply hopper 28 has a capacity onlyslightly greater than that of a skip load and since the diameter of thehopper is less than that conventionally employed, inequalities in theupper level of the material in the hopper as the result of thedirectionalized delivery from the skip represent only a relatively smallpercentage of the total depth of the material in the hopper, so that thematerial is substantially uniformly distributed over the bell 29. As theskip or bucket returns for another load of material, the bell 29-islowered through operation of its actuating tube 31, thus discharging thecontents of the hopper 28 into the hopper 26, the bell 2'! being closedat this time. Since the material within the upper hopper 28 issubstantially uniformly distributed therein, this material in movingdownwardly, upon opening of the bell 29, will be substantially uniformlydistributed over the bell 2'! for the hopper 26.

Preferably the bell 2? is operated after each delivery of material tothe hopper 2% to, in turn, charge the material into the area within thetube 32. At this time the deflecting means 35 is so positioned, throughoperation of'the ring 44, that the material discharging from the hopper26 is guided to the desired location within the tube 32. That is to say,with the deflector 35 so disposed that the plates 36 extendsubstantially vertically downwardly, as shownin Fig. 4, the distributionof the material discharging from the hopper 26 is controlled simply bythe shape of the bell 2?, the-nature of the material, and the dimensionsof the tube 32. Where the particles of the material charged roll easily,such as large coke or relatively large pieces of flux, the deflector 35may be positioned, as just mention, to extend substantially vertically,so that the particles strike the inner side wall of the tube 32 andbound therefrom to their resting place. However, where the materialcharged is relatively fine, as, for example, ore containing a largepercentage of fines, the deflecting means 35 may be positioned tointercept the material as it falls and direct it either against theouter side wall of the tube 33 or to intermediate positions between thetube 33 and the tube '32. The particular position of the deflectingmeans is, of course, selected in accordance with the material handledand may be varied for each separate operation of the bell 2? if theoperator so desires.

As mentioned above, in the preferred embodiment of the procedure the oreis charged separately from the other materials and is so directed by thedeflector 35 as to form a substantially uniform layer of annular formbetween the tubes 32 and 33, one of the layers of ore being designated 0in Fig. 1. The coke is preferably sized to separate the fines therefromprior to charging and the coarse coke is charged before and after theore forming annular layers C intermediate the tubes 32 and 33. Thefiuxing materials may be charged with the large particles of coke or maybe separately charged intermediate a coke and ore layer. By employ-- ingtube 33 and the deflecting means 35, the large particles of coke and offluxing materials are prevented from entering the central portion of thefurnace, thereby preventing the formation of a very porous andrelatively unrestricted passageway for gases therethrough.

The fine coke, which was separated before charging, is preferablycharged into the interior of the tube 33 by operation of the bell 2'!and adjustment of the deflecting means 35 to direct the coke fallingfrom the bell into the tube 33, see Fig. 2. This fine coke prevents theformation of a too porous center in the stock column and at the sametime eliminates the necessity of charging ore to the center to overcomethis undue permeability, as is customary in conventional practice.Moreover, the fine coke provides a path of controlled permeability andinsures that this coke will not interfere with porosity through thelarge particles of coke, flux, and the ore layers by filling the voidstherein. In addition to facilitating charging of the fine coke to thecenter, the tube 33 prevents this coke from being mixed with the othermaterials until after the materials enter the main body of the furnacethereby insuring that the distribution achieved within the tubes 32 and33 will be substantially maintained throughout the descent of thematerials through the upper portion of the furnace, since the severallayers are not subjected to appreciable agitation as they movedownwardly.

Preferably, the rate of charging, by virtue of the operation of the skip45 and of the bells 21, 29, is such that the upper level of materialwithin the tube 32 and tube 33 is above the lower edges of these tubesduring normal operation of the furnace. Therefore, since the wall ortube 32 is impervious and is sealed to the top of the furnace, the zoneor enclosed space within the tube 32 is substantially free of upwardlyrising currents of gases, the latter being channeled around this zone tothe gas outlets 22, 23. Therefore, the charging of materials into thisrela- 'tively quiescent zone, which is not in direct cornmunication withthe gas outlets, greatly reduces dusting and turbulence, therebyinsuring a more uniform distribution of the materials and materiallyreducing loss of fine materials in the form of dust. This factor, aswell as the control of the porosity of the stock column by the layeringmethod of charging, enables a larger percentage of ore fines to beemployed than can now be utilized with conventional methods andapparatus.

The materials delivered. into the relatively quiescent zone within thetubes 32 and 33 move downwardly during normal operation of the furnaceand maintain the level SL of the stock within the furnace propersubstantially constant at a point adjacent th lower edge of the tubes,the slope of this stock level depending upon the dimensions of the tube32 with respect to the furnace, the angle of repose of material, and thelike. Since the upper level of materials within the tubes 32, 3 ismaintained above the lower end thereof, these tubes provide what may, in

effect, be termed a constant head feeder, since regularities in the rateof operating the bells.

Therefore, the layers of the material established within the tubes aresubstantially maintained within the furnace proper with the result thatthe stock column has a controlled porosity and an optimum distributionof material for the reducing operation. Since the fine coke within thetube 33 has been maintained out of contact with the other materials, asthe layers thereof were being established, the said fine coke tends tocontinue as a discrete core at least in the upper portion of thefurnace, thereby controlling the porosity through this portion of thefurnace and preventing channeling of the reducing gases therethrough.

The improved method of charging by means of the concentric tubes and thedeflecting means disclosed may be readily employed in a conventionalfurnace without appreciable alteration therein since, while the tubesand deflector somewhat decrease the height of the stock column in thefurnace, this is compensated for by the improved distribution of thecharge and controlled porosity thereof which affords a more efiicientoperation and removes the necessity of using excessive pressures on thegases supplied to the tuyeres. In order that the velocity of the gasesissuing from the top surface of the stock column be not materiallyincreased and to obtain optimum use of the rising gases, it is desirablethat the area between the outer surface of the wall or tube 32 and theupper portion of the lining 2| above the wear plates 22 be substantiallythe same as in the area of the furnace below the upper edge of the wearplates 22. To accomplish this, the upper portion of the furnace abovethe wear plates 22 may be increased in diameter, although by suitableselection of the diameters of the tubes 32, 33, the invention may beadvantageously employed without material alteration in the diameter ofth furnace.

By way of example, it may be stated that the diameter of the outer tube32 may be such as to provide an area which is between 35% and 60% of thearea of the furnace in the region of the wear plates 22, while the innertube 32 will have a diameter such as to be in the order of 5% to of thisarea. For example, where the diameter of the furnace in the region ofthe wear plates 22 is 20 feet, the diameter of the outer tube 32 may bebetween 11.8 and 15.6 feet while the diameter of the tube' 33 may befrom 4 /2 to 10 feet. The corresponding diameter of the interior ofthe'furnace above the'wear plates would then be'from 23.2to25.2 Y

The larger the area within the tube 33 the greater is the necessity toslow down flow of gases through the corresponding center of the furnaceby means of the fine coke, whilethe larger the area between the tubes 32and 33 the thinner can be the ore layers deposited therein.These'variations, corresponding with a particular installation, areunder control of the operator by variation of the amount deposited ineach layer and by varying the order in which material is delivered bythe skip. That is to say, where a thicker layer is to be deposited, anextra skip load of ore may be delivered before the coke in which eventthe bell 21 need not be operated for eachskip load deposited but onlywhen the type of material charged is changed. The necessary prerequisiteis that the ore be spread thinly and uniformly entirely around theperiphery of the furnace and this is accomplished in a broader and moreuniform band than is possible without using this method. The sizing ofthe ore and charging-the coarser portions between the concentric tubesin layers renders the resulting bands of ore and coke more permeable,while the fine coke charged to the center prevents too much of thereducing gases from channeling therethrough. Moreover, by employing theconcentric tubes, the flux material such as limestone, which rollsrelatively easy, is kept out of the center where it would promote anundesired porosity, the flux materialbeing more uniformly scatteredthroughout the charge, thereby promoting mor uniform fiuxing action. Byproper use of the deflector 35, it'is possible to control the depositingof the material radially in the annulus between 32 and 33 so that theore layer is of uniform thickness or thicker at either end or in themiddle of the annulus as may be desired or necessary for a particularinstallation. The resulting more uniform permea bility of the stockcolumn promotes more efficient and rapid reduction and a more uniformmovjement of the solid materials in the furnace, there-- by reducinghanging and slipping. As mentioned above, the material shouldbesubstantially uniformly distributed on the upper bell 23 and one way ofeffecting this is to make the upper or supply hopper 28 of smallerdiameter than conventionally employed for a furnace of given dimensions.Other means'for effecting this result may be employed with supplyhoppers of conventional size. Figs. 5 and 6 illus trate an example ofone'such means. Asshown therein, the wall of the upper hopper 28, whichmay be either small or large diameter, isp'ro' vided with a deflectorplate 46. Preferably this plate is fixed to the wall and extends onlypartially thereabout being located principally on the side of the hopperopposite the lower edge of the skip or bucket 45. The deflector isinclined inwardly and downwardly in a manner to defiect a portion of thematerial striking the side wall of the hopper, as it discharges from theinclined skip, and 'direct it across the hopper uniform height thereof.As shown therein, a rotatable scraping arm or arms 4! are-fixed atthe'lower end of a hollow tube48 extending upwardly in spacedrelationship with respect to the bell operating tube 13! The upper .endof the tube -48 is provided with a worm gear .49, the

.tube and :gear being supported by bearings *5!) ,on astationarysupporting plate'5i, the gear being driven by means of a worm 52 throughthe mechanism :not shown. By this arrangement, material delivered to thehopper 28 by means of the skin is levelled by the rotation of the-bladeor blades 41 which-may be either continuously or intermittentlyoperated.

It has been found that the efiective or active .area in front of eachtuyre is limited. The estimated dimensionsof this effective or activearea vary somewhat but evidently does not exceed 6 feet as measuredradially of thefurnace. Consequently, as the diameter of furnaces havebeen increased, to increase capacity, there develops a dead centersubstantially through the heart of :the'coreofthe furnaceto which theair and other gases from thetuyres does not directly penetrate.Therefore, with the'larger size con- .vention-al furnaces operated inthe conventional manner, ore charged into the center of the furnace tocontrol the porosity therethrough finds :its way to the hearthwithoutbeing reduced and hence must 'be'reduced in this melting or smeltingzone by direct contact with incandescent carbon. As is well-known, thistype of reduction is wasteful of coke and slows the operation. Theimproved apparatus and procedure described above with respect to Figs. 1to 8 overcome this dimculty by keep ng the ore out of the center ofthezfurnace and allowing only fine coke to descend therethrough where itis available for supplying heat and/or reducing gasesupon encounteringthe heat of the melting or smelting zone; the ore, being in-an annulus,issubjected to the reducing gases during its descent and hence reachesthe melting zone as metallic iron. Consequently, in addition to theconsiderations mentioned above asdeterminative-of the dimensions of thetubes.32, 33, there must also-beconsidered the diameter of thefurnace'and the corresponding .dimensionof the dead center, as it iscalled, since the diameter of-the innertube33 should be in the order ofthis dimension.

In -.order to eliminate the above-mentioned dead center, proposals havebeen made heretofore for employment of furnaces having eitherrectangular or elliptical hearths. Furnaces of this configuration havenot, however, been adopted probably because of the difficulties ofproperly charging them, since the conventional circular bells andhoppers'are not adapted thereto. In accordance with this invention, theimproved method of charging may also be adapted to use with furnaces ofrectangular or elliptical cross section which have their tuyeres soarranged:asitosubstantially or completely eliminate the dead center.Thus,.Fig. 9zshows a furnace 53 of rectangular configurationihaving thetuyres ilarrangedinpairs on opposite sides'thereof so that the activeareas thereof, indicated at 5.5 in

.Fig. 10, substantially meet. To eflect-chargingof such a furnace, theupper portion thereofqisprovided with a rectangular partition wall 56intermediate the charging bells and the gas outlets E! and 58, therebydefining anopen bottomed enclosure into which the materials are to becharged, thisenclosure corresponding to the tube 32 :of the preferredembodiment. Since there is now no dead center, there is no'need for acentral'tube corresponding to the tube 33 and hencenone is provided.

To'efiect charging of a furnace of this nature, the top thereof isprovided with a charging hopper 59 of generally rectangular crosssection having downwardly converging side walls, the open end beingclosedby-a charging bell 1600f substantially rectangular configurationwith downwardly sloping side walls. The upper portion of the hopper 59is in communication with the lower end of a supply or-feed hopper 5|which may be constructed similar to the charging hopper '59 and isprovided with an upperor small bell-62 similar to the hell 6!], theconfiguration oi bell 62 being shown in Fig. 12.

In order to supply material to the hoppers and bells and properlydistribute the material therein, one or more conveyors are provided, twosuch conveyors, 63 and 64, being illustrated. These conveyors are eachpreferably positioned to extend longitudinally with respect to thelargertransverse dimension of the supplyhopperfil and are so constructed thatthe delivery ends of :the conveyors are movable backwardly and forwardlyover thehopper ii to deposit the material substantially uniformlytherein. One suitablezform of conveyor operating in this manner is .of'the endless belt type in which the forward roller or drum for the upperflight of the belt is mounted on a reciprocating frame.

As somewhat schematically illustrated in Fig. 11, each of the conveyorsE53, .64 comprisesan endless belt 65 trained about supporting rollers ordrums such as 65, 61 and'fifi, the belt being driven by conventionalmechanism, not shown, associated with one of the rear belt supportingrollers or drums, not shown. The drum of roller 66 is supported uponspaced bars 69 and TH adjacent the forward ends thereof, these barsbeing longitudinally-movable relative to the main frame of the conveyorby being movably supported in stationary channel shaped members H and72. The belt roller or drum 6% is supported by brackets l3 and '54extending downwardly from the stationary channel members "H and T2,respectively, while roller or drum 6'! is supported for movement withthe bars 59 and 18 by being journalled in brackets 15 and .76 connectedwith the bars .69 and 'Ili. The bars '69 and H3 are longitudinallyreciprocated by any conventional mechanism thus moving the delivery endof the belt 65 and the roller '5? from their positions shown in fulllines in Fig. 11 to the positions shown in broken lines in the samefigure. Since the belt is being driven at the same time, :any materialon its upper surface is depositedin the hopper 61 substantiallyuniformly throughout the cross sectional area thereof. In view of thesloping nature of the bell 82 it is not necessary that the belt 65 havea width equal to that of the hopper 5! nor is it necessary that the beltbe reciprocated a distance equal to the entire length of the hopper.

Material is preferably supplied to the belt'ili, for delivery tothehopper 6|, in a manner such a to provide substantially'uniformdistribution of the material over the entire width of the belt. This isreadily effected by employing supply bins for the materials thedischarge openings of which are substantially equal to the width of theconveyor belt. In the illustrated form three such supply bins areindicated for the belt 65, although a greater or lesser number may beutilized. As shown, bin ll is provided with one type or grade of ore,bin 18 with a second grade or type of ore, while bin 19 may containpellets or agglomerates of fine ores.

The conveyor 64 is identical in construction and operation with theconveyor 63 and hence will not be described in detail. As shown, threesupply bins are also provided for this conveyor. Bin 80 may, for examplecontain fine coke, bin 8| may contain coarse coke, while bin 82 maycontain limestone or other flux material. Of course, other materials maybe provided in the bins and more than one bin may contain the samematerial if desired. The conveyor 64 has the delivery end thereofreciprocated over the hopper 61 in the same manner as described forconveyor '63, one conveyor being advanced while the other is beingretracted, or remains in its retracted position, thereby preventinginterference therebetween.

The actuating rods and tubes for the bells are preferably provided Withintermediate yoke portions to accommodate the ends of the conveyors 63and 64 so that the latter may be reciprocated over the hopper 6|, asdescribed above. Thus, as shown in Fig. 9, the actuating rods 83 for thelower bell 6B are each provided with an intermediate substantiallyrectangular shaped yoke portion 84 providing an opening for passage ofthe conveyors 63, $4. The actuating tubes 85 for the upper bell 62likewise are each provided with a rectangularly shaped yoke portion 86which surrounds the yoke 84. While two spaced rods and surrounding tubesare shown, it will be apparent that a single rod 83 and tube 85 could beused if desired, provided the connections to the respective bells aresuch as to prevent tilting of the bells. I

In a furnace as shown in Figs. 9 through 12, the conveyor belts arepreferably sequentially operated to sequentially deliver ore, coke, andflux to the upper hopper 6! when the bell 62 thereof is closed, eachmaterial thus delivered being equal in amount to that necessary to forma layer of such material of desired thickness within the fur nace. Thebell 62 is then operated after delivery of each material and while thebelts are not delivering material, to deposit the material in the hopper59 upon the bell 66, the latter bein closed at this time. While the bell62 is next closed. a different material is delivered to the hopper 6! byone of the conveyors and the material within the hopper 58 is thendelivered to the interior of .the enclosure provided by the partition 56by operation of the bell Bil, the configuration of this bell acting tosubstantially uniformly deposit the material in a layer within theenclosure. While not shown, it will be apparent that an adjustabledeflecting means may be employed within the tube 56, if desired, to aidin this distribution. Instead of sequentially operating the conveyorsand bells for each material, these devices may be operated to depositmore than one material at a time at one drop or actuation of the bell60.

As in the preferred embodiment, the delivery of material to the upperhopper and the operation of the bells is so timed that the level ofmaterial 'cated by the broken line 81.

within the enclosure 56 is maintained above the lower end of thatenclosure so as to segregate the interior thereof from the rising gasesand serve as a constant head feeder of material to the furnace.Therefore, the layered material within the partition or enclosure 56moves downwardly subjection to rising currents of gases and hence a moreuniform distribution is effected with less loss of fine material than inconventional practice. Moreover, the layering of the material provides acontrolled porosity throughout the furnace which is further maintainedsubstantially uniform by virtue of the fact that the stock level ofmaterial within the furnace remains substantially unaltered even thoughthe rate of operation of the bells is not uniform.

A similar construction to that shown in Figs. 9 through 12 may beemployed for use with a rectangular furnace 88 having staggered tuyeres89 as indicated at Fig. 13, it being understood that in both of theserectangular furnaces the capacity of the furnace is increased byaltering only one transverse dimension thereof, while maintaining theother dimension substantially equal to the effective active area infront of the tuyeres.

The principles of this invention may also be employed with a furnace athaving an elliptically shaped hearth, with the tuyeres 9| arranged asindicated in Fig. 14. In this event, the charging mechanism would besubstantially similar to that shown in Figs. 9 through 11 except thatthe partition wall should preferably be altered to substantiallycoincide with the configuration of. the furnace wall and the charginghoppers and bells should be provided with rounded ends so as to besubstantially a flat ellipse in cross section.

It will be apparent that a furnace constructed either as shown in Figs.1 to 8, or as shown in Figs. 9 to 14, and operated in accordance withthe improved procedure of'this invention provides a more uniformpermeability of the stock column, maintains the latter substantially atconstant height, and enables the material to be charged into arelatively quiescent zone, thereby greatly reducing dusting.Consequently, the furnace may be operated with a more uniform volume andpressure of air or other gas and will produce metal of more uniformanalysis at a higher production rate and with a lower consumption ofcoke per ton of metal produced. Furthermore, ores containing a largerpercentage of. fines may be employed and slipping, hanging, and otheroperational difficulties are substantially eliminated. Moreover, theimproved procedure and apparatus of the preferred form may be employedin conventional furnaces without appreciable alteration thereof bysimply altering the top thereof slightly.

Numerous variations in the method will be apparent to those skilled inthe art after having had the advantage of this disclosure. For example,the deflector plates 36 shown in Figs. 1 to 3 may be individuallyoperated, if desired, by employing separate actuating rods for the shoe39 of each plate. Likewise, the shape of the several hoppersand bellsmay be varied, or means other than those shown in Figs. 1, 5 and 'l maybe employed for effecting a more uniform distribuaeznor'r tionmf thematerial :imthe' upper or rfeedingshoptper. Moreover, when employing :arectangular :or :ellip'tical 'furnace, :the :central area 'of the-topnnay be utilized for 'the withdrawal of gases, charging :then ibeing:eifected "through two sets nf charging mechanisms extendinglongitudinally of the greater transverse dimension of the .furmaceoneither side ofithe "central area. Furtherzmore,'the=order of chargingthe materialsimaybe varied :from that disclosed. These and nther:variations, whichmay be' eifected'bythose skilled .infthe art, :arecontemplated as coming within ,ithezscopeof the invention, thespecificdescripition anddrawings being'intended only as illusitra'tive.

fHavingthus described the invention, I:olaim:

d. The :method of charging ore, coke and flux -materialsintora blastfurnace comprising, separating the coke into portions of fine particlesand melatively coarseparticles, establishing a first zone substantiallyfreeof upwardly rising currents of :gas within the upper portion of the"furnace in communication with the charging opening 'o'fthe ffurna'ceandspaced inwardly from the'side walls of said furnace with the interior oithe furnace being in-communication with the said zone only at-the lowerend of the latter, establishing a secon'd 'substantially gas free zoneinteriorly of the ffirst'zone and communicating with the charging-:opening and the-interior of the furnace, the lower endsiof-said:zones'being-at substantially the same elevation within the'furnace and the cross-sectiondl area:ofsaid'second-zone being in theorder of to 25% or the cross-sectional area of the interior of thefurnace adjacent the lower ends of said zones, withdrawing the gasesfrom said furnace exteriorly of said zones, charging'the ore, fluxandcoarse coke into said first zone exteriorly of said second zone andcharging the fine coke into the interioro'f said second zone, the rateof charging of the materials to said zones being such that the level ofmaterial in each 'iscontinuously maintained above the lower end thereofthereby excluding'furnace gases therefrom with the fine coke preventedfrom mixing with the other charged material until after passage thereoffrom said zones.

'2. The method of charging ore, coke and flux materialsinto a blastfurnace comprising, separating-the'coke into'portions of fine particlesand relatively coarse particles, establishing a first zoneysubstantiallyfree of upwardly rising currentso'f gas "within the upper portion of thefurnacein communication with the charging ,opening-of the furnace andspaced inwardly from the side "walls of the said furnace with-theinterior of the furnace being in communication 'with'the said zoneonlyat the lower end of the latter, establishing a second substantiallygas free zone interiorly of the'first zone and communicating withthechargingopening and the interior of the furnace, "the lower ends ofsaid zones being at substantially the 'same elevation within the furnaceand the cross-sectional area of said .second zone being in the order of5% to 25% of the cross-sectionalarea of the interior oi the furnaceadjacen'tithe lower ends of said zones, withdrawing the gases from saidfurnace exteriorlyof said zones, separatelylcharging the ore, -flux andcoarse coke into said first zone exteriorly of said second zone toprovide layers of these materials ;in .said firstzone, and charging thefine coke ,only ,into thelinterior nfsaid second zone, theirateofohara.ingofdihe materials ito said zone being such-that *the level of thematerial in *each is continuously maintamed-abovethe lower end thereofthereby excluding furnace gases therefrom with the fine coke preventedfrom mixing with the other charged-materials-until after passage thereoffrom said zones.

3. The-method of charging ore, coke and flux materials into a blastfurnace equipped with a charging bellycomprising separating thecoke intoportions of fine particles and relatively -coarse particles,establishing a first zone substantially free of upwardly risingcurrentsof gas within the upper portion of the furnace in communication with thecharging bell and spaced inwardly from the side walls of the furnacewith the interior of therfurnac'e being in communication withrthe saidzone only at the lower end of the latter, establishing a.secondsubstantially gas free'zone interiprly of the first zone andcommunicating with the charging 'bell and the interior of the furnace,the lower end of said zones being at substantiallythe same elevationwithin the furnace and the cross-sectional area of said second zonebeing in the order of 5% to 25% of the cross-sectional'area of theinterior of the furnace adjacent the lower ends of said zones,withdrawing the gases from said furnace exteriorly of said-zones,depositing the ore, flux, coarse and fine coke separately upon thecharging bell in a manner-to provide a substantially uniformdistribution of each material thereon, sequentially operating thecharging bell to separately drop the ore, flux and coarse coke into saidfirst zone exteriorly of the second zone, operating the charging bell todrop the fine coke into said second zone, the rated charging of thematerials to said zones being-such that the level of the material ineach is continuously maintained'above the lower end thereof therebyexcluding furnace gases therefrom with the fine coke prevented frommixing with the other charged materials until after passage thereof fromsaid zones.

KENNETHC. MCCU'I'CHEON.

:References Cited in the file of this patent UNITED STATES PATENTS.Number Name Date 16,560 Weissenborn Feb. 3, 1857 495,675 Huber Apr. 18,1893 727,754 Cromwell May 12, 1903 783,044 Johnson Feb. 21, 1905 796,784Witherbee et a1. Aug. 8, 19.05 906,717 Johnson Dec. 15, 1908 959,484Dwight May v31, 1910 1,031,478 Smith July 2, 1912 1,167,883 .BoyntonJan. 11, 1916 1,267,004 Slick May 21, 1918 1,267,005 Slicl: May '21,.1918 1,945,341 Brassert Jan. .30, 1934 2,050,379 Rice Aug. 11, 19362,155,927 Boynton Apr. 25, 1939 2,208,245 vBoynton July 16, 1940 FOREIGNPATENTS Number Country Date 11,879 Great Britain of 1902 398,963 GermanyJuly 24, 1924 OTHER REFERENCES Blast Furnace and-Steel Plant, July.l936,-pages 6031x0606. Published :bywsteel Publications,; -Inc.,.Qsceola Mills, Pa.

1. THE METHOD OF CHARGING ORE, COKE AND FLUX MATERIAL INTO A BLASTFRUNACE COMPRISING, SEPARATING THE COKE INTO PORTIONS OF FINE PARTICLESAND RELATIVELY COARSE PARTICLES, ESTABLISHING A FIRST ZONE SUBSTANTIALLYFREE OF UPWARDLY RISING CURRENTS OF GAS WITHIN THE UPPER PORTION OF THEFURNACE IN COMMUNICATION WITH THE CHARGING OPENING OF THE FURNACE ANDSPACED INWARDLY FROM THE SIDE WALLS OF SAID FURNACE WITH THE INTERIOR OFTHE FURNACE BEING IN COMMUNICATION WITH THE SAID ZONE ONLY AT THE LOWEREND OF THE LATTER, ESTABLISHING A SECOND SUBSTANTIALLY GAS FREE ZONEINTERIORLY OF THE FIRST ZONE AND COMMUNICATING WITH THE CHARGING OPENINGAND THE INTERIOR OF THE FURNACE, THE LOWER ENDS OF SAID ZONES BEING ASUBSTANTIALLY THE SAME ELEVATION WITHIN THE FURNACE AND THECROSS-SECTIONAL AREA OF SAID SECOND ZONE BEING IN THE ORDER OF 5% TO 25%OF THE CROSS-SECTIONAL AREA OF THE INTERIOR OF THE FURNACE ADJACENT THELOWER END OF SAID ZONES, WITHDRAWING THE GASES FROM SAID